Access local Sage notebook online

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I am running Sage 6.3. I have used Sage for a while, and I open a session on my Linux box using

home@home:~$ sage notebook

which open at http://localhost:8080/home/admin/16/This means the notebooks I then write are saved in directory ~/.sage/sage_notebook.sagenb/home/ and I understand the command sage: notebook("path/to/directory") allows one to specify an alternative to the default directory, for example if you want to work out of Dropbox. I require a couple of clarifications:

1. I cannot find .sws files in the default directory. I assume this is what I am looking for
2. How does the online notebook link with my local setup. How do I get a username and password for this? Is there some way my local work can automatically sync with the online notebook, so it is like a cloud? Is this the purpose of the online notebook--please give a detailed explanation of the online notebook, and why does it have two different web URLs?
3. Also note, I am aware of sagemathcloud, and I have found it slow and buggy in the past. I would prefer to use sagenb for the time being, although I would welcome criticism if this seems unwise. Once concern of mine is that the sagemathcloud does not use the same file extensions as sagenotebook (.sws)